Pub Date : 2022-07-27DOI: 10.17159/wsa/2022.v48.i3.3913
Hassan Heidari, Zhaleh Zarei, Kazhal Mohammadi
Water is one of the most important environmental factors in agriculture. Drought annually damages agricultural products. This loss can be reduced by some strategies. Pot and field experiments were conducted to assess the effect of wick irrigation on growth, yield and water use efficiency of maize, foxtail millet, and bitter vetch. Irrigation treatments included wick and surface irrigation (control) methods. Results of the pot experiment showed that wick irrigation had higher total fresh weight, total dry weight, and water use efficiency as compared to surface irrigation in both foxtail millet and bitter vetch. In foxtail millet, wick irrigation also had higher leaf to stem ratio, plant height, leaf relative water content and leaf area compared to surface irrigation. Results of the field experiment showed that wick irrigation increased specific leaf weight, water use efficiency, stem diameter, leaf fresh weight, total fresh weight, leaf dry weight, total dry weight, and leaf to stem ratio, but had similar fresh and dry stem weight and plant height compared to surface irrigation in maize. It is likely that the reduction in surface evaporation, reduced water consumption, and increased dry matter resulted in increased water use efficiency in wick irrigation. Overall, wick irrigation had higher water use efficiency, biomass, and plant growth compared to surface irrigation in maize, foxtail millet and bitter vetch.
{"title":"Improving water use efficiency and biomass in maize, foxtail millet, and bitter vetch by wick irrigation","authors":"Hassan Heidari, Zhaleh Zarei, Kazhal Mohammadi","doi":"10.17159/wsa/2022.v48.i3.3913","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i3.3913","url":null,"abstract":"Water is one of the most important environmental factors in agriculture. Drought annually damages agricultural products. This loss can be reduced by some strategies. Pot and field experiments were conducted to assess the effect of wick irrigation on growth, yield and water use efficiency of maize, foxtail millet, and bitter vetch. Irrigation treatments included wick and surface irrigation (control) methods. Results of the pot experiment showed that wick irrigation had higher total fresh weight, total dry weight, and water use efficiency as compared to surface irrigation in both foxtail millet and bitter vetch. In foxtail millet, wick irrigation also had higher leaf to stem ratio, plant height, leaf relative water content and leaf area compared to surface irrigation. Results of the field experiment showed that wick irrigation increased specific leaf weight, water use efficiency, stem diameter, leaf fresh weight, total fresh weight, leaf dry weight, total dry weight, and leaf to stem ratio, but had similar fresh and dry stem weight and plant height compared to surface irrigation in maize. It is likely that the reduction in surface evaporation, reduced water consumption, and increased dry matter resulted in increased water use efficiency in wick irrigation. Overall, wick irrigation had higher water use efficiency, biomass, and plant growth compared to surface irrigation in maize, foxtail millet and bitter vetch.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"12 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76851875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-27DOI: 10.17159/wsa/2022.v48.i3.3929
Sogand Arab, Javad Mozaffari, Mohammad Javad Nahvivia
Nitrogen compounds added to the soil may convert to nitrate and cause contamination. The distribution and uniformity of soil nitrate in surface vs. subsurface drip irrigation systems were compared in a physical model consisting of a transparent glass box (1.20 x 0.5 x 1 m) and sandy loam soil, and considering emitter installation depths of 0 and 30 cm, discharge rates of Q1 = 2, Q2 = 4, Q3 = 8 L/h, and fertilizer levels of S1 = 125, S2 = 250, S3 = 375 mg/L. Irrigation continued for 6 h and nitrate and moisture sampling was performed for 68 h after the initiation of water front advance. The result showed that doubling the discharge caused the wetted area to triple in size in the subsurface drip irrigation system whereas it only doubled in size in the surface drip irrigation system. Thus in the subsurface system, when increasing the fertilizer level, the nitrate spread out extensively and therefore its concentration was greatly reduced. Also, by increasing discharge, the difference in soil nitrate concentration between the two systems increases because of increasing non-uniformity of nitrate distribution in the surface system, such that by increasing the fertilizer concentration form 125 to 375 mg/L, the difference in nitrate concentration increases from 22% to 500% (for Q1 = 2 L/h), 43% to 352% (for Q2 = 4 L/h), and 14% to 166% (for Q3 = 8 L/h). Thus the subsurface drip irrigation system has a more uniform trend of nitrate distribution than the surface drip irrigation system. Also, treatment with maximum flow and fertilizer level will create the most optimal nitrate concentration in the soil.
{"title":"Evaluation of nitrate redistribution in surface and subsurface drip irrigation systems","authors":"Sogand Arab, Javad Mozaffari, Mohammad Javad Nahvivia","doi":"10.17159/wsa/2022.v48.i3.3929","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i3.3929","url":null,"abstract":"Nitrogen compounds added to the soil may convert to nitrate and cause contamination. The distribution and uniformity of soil nitrate in surface vs. subsurface drip irrigation systems were compared in a physical model consisting of a transparent glass box (1.20 x 0.5 x 1 m) and sandy loam soil, and considering emitter installation depths of 0 and 30 cm, discharge rates of Q1 = 2, Q2 = 4, Q3 = 8 L/h, and fertilizer levels of S1 = 125, S2 = 250, S3 = 375 mg/L. Irrigation continued for 6 h and nitrate and moisture sampling was performed for 68 h after the initiation of water front advance. The result showed that doubling the discharge caused the wetted area to triple in size in the subsurface drip irrigation system whereas it only doubled in size in the surface drip irrigation system. Thus in the subsurface system, when increasing the fertilizer level, the nitrate spread out extensively and therefore its concentration was greatly reduced. Also, by increasing discharge, the difference in soil nitrate concentration between the two systems increases because of increasing non-uniformity of nitrate distribution in the surface system, such that by increasing the fertilizer concentration form 125 to 375 mg/L, the difference in nitrate concentration increases from 22% to 500% (for Q1 = 2 L/h), 43% to 352% (for Q2 = 4 L/h), and 14% to 166% (for Q3 = 8 L/h). Thus the subsurface drip irrigation system has a more uniform trend of nitrate distribution than the surface drip irrigation system. Also, treatment with maximum flow and fertilizer level will create the most optimal nitrate concentration in the soil.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"40 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76175260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-27DOI: 10.17159/wsa/2022.v48.i3.3939
LP Tshapa, G. Naidoo, Sershen, KK Naidoo
Water scarcity has led to increased use of wastewater, particularly greywater, for crop irrigation. This study investigated whether the addition of yeast can alleviate the potential negative effects of greywater use on lettuce (Lactuca sativa L.) and maize (Zea mays L.). Seeds and seedlings were treated with 4 concentrations (0.005; 0.01; 0.015 and 0.020 g‧mL−1) of yeast-treated tapwater (YTW) and greywater (YGW). Tapwater (TW) and greywater (GW) without yeast served as controls. In general, an increase in yeast concentration compromised seed germination in Petri dishes, but improved germination in soil. Tapwater was more effective than GW in promoting germination and growth in both species. Lower concentrations of yeast generally increased germination capacity in both species compared to the controls. Total biomass, number of leaves, chlorophyll content, leaf area, photosynthetic rate and maximum quantum yield of photosystem II (Fv/Fm) were significantly higher in yeast treatments in both species, compared with the controls. Biomass accumulation, total leaf area, chlorophyll content and photosynthesis were higher in YGW than controls and YTW. Differences in biomass allocation between treatments may be due to changes in soil moisture, pH and electrical conductivity of the soil caused by yeast supplementation. This study showed that plants treated with YGW performed better than those treated with YTW and without yeast. Yeast supplementation of greywater could increase water recycling and provide a cheap bio-fertilizer to home growers, whilst significantly improving yield in both species. This innovative approach may enhance water and food security of subsistence farmers in rural areas.
{"title":"Yeast supplementation alleviates the negative effects of greywater irrigation on lettuce and maize","authors":"LP Tshapa, G. Naidoo, Sershen, KK Naidoo","doi":"10.17159/wsa/2022.v48.i3.3939","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i3.3939","url":null,"abstract":"Water scarcity has led to increased use of wastewater, particularly greywater, for crop irrigation. This study investigated whether the addition of yeast can alleviate the potential negative effects of greywater use on lettuce (Lactuca sativa L.) and maize (Zea mays L.). Seeds and seedlings were treated with 4 concentrations (0.005; 0.01; 0.015 and 0.020 g‧mL−1) of yeast-treated tapwater (YTW) and greywater (YGW). Tapwater (TW) and greywater (GW) without yeast served as controls. In general, an increase in yeast concentration compromised seed germination in Petri dishes, but improved germination in soil. Tapwater was more effective than GW in promoting germination and growth in both species. Lower concentrations of yeast generally increased germination capacity in both species compared to the controls. Total biomass, number of leaves, chlorophyll content, leaf area, photosynthetic rate and maximum quantum yield of photosystem II (Fv/Fm) were significantly higher in yeast treatments in both species, compared with the controls. Biomass accumulation, total leaf area, chlorophyll content and photosynthesis were higher in YGW than controls and YTW. Differences in biomass allocation between treatments may be due to changes in soil moisture, pH and electrical conductivity of the soil caused by yeast supplementation. This study showed that plants treated with YGW performed better than those treated with YTW and without yeast. Yeast supplementation of greywater could increase water recycling and provide a cheap bio-fertilizer to home growers, whilst significantly improving yield in both species. This innovative approach may enhance water and food security of subsistence farmers in rural areas.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"21 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78204902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Precipitation interpolation is widely used to generate continuous rainfall surfaces for hydrological simulations. However, increasing the precision of values at the unknown points generated by different spatial interpolation methods is challenging. This study used the Chaohe River Basin, which is an important source of Beijing’s drinking water, as a research area to comprehensively evaluate several precipitation interpolation methods (Thiessen polygon, inverse distance weighting, ordinary kriging and ANUSPLIN) for inputs in hydrological simulations. This research showed that the precipitation time-series surface generated using the ANUSPLIN interpolation method had higher accuracy and reliability. Using this precipitation input to drive the hydrological models, we explored the parameter uncertainties of four typical hydrological models (GR4J, IHACRES, Sacramento and MIKE SHE) based on the multi-objective generalized likelihood uncertainty estimation (GLUE) method. The GLUE method was used to study the parameter sensitivity and uncertainty of the model. Results showed that the ANUSPLIN precipitation interpolation surface combined with the Sacramento model performed best. The multi-objective GLUE method had obvious advantages in parameter uncertainty analysis in hydrological models. Simultaneously exploring the convex line and point density distributions of the behavioural parameters with multi-objective functions determined their distribution and sensitivity more effectively.
降水插值被广泛应用于水文模拟中生成连续降雨面。然而，如何提高不同空间插值方法生成的未知点上的值的精度是一个挑战。本研究以北京市重要的饮用水源巢河流域为研究区域，综合评价了几种降水插值方法(Thiessen多边形、逆距离加权、普通克里格和ANUSPLIN)在水文模拟中的输入。研究表明，采用ANUSPLIN插值方法生成的降水时间序列面具有较高的精度和可靠性。利用降水输入驱动水文模型，基于多目标广义似然不确定性估计(GLUE)方法，探讨了GR4J、ihaacres、Sacramento和MIKE SHE 4种典型水文模型的参数不确定性。采用GLUE方法对模型的参数敏感性和不确定性进行了研究。结果表明，结合萨克拉门托模型的ANUSPLIN降水插值面效果最好。多目标GLUE方法在水文模型参数不确定性分析中具有明显优势。同时用多目标函数探索行为参数的凸线和点密度分布，更有效地确定了它们的分布和灵敏度。
{"title":"Assessment of multiple precipitation interpolation methods and uncertainty analysis of hydrological models in Chaohe River basin, China","authors":"Binbin Guo, Jing Zhang, Tingbao Xu, Yongyu Song, Mingliang Liu, Zhong Dai","doi":"10.17159/wsa/2022.v48.i3.3884","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i3.3884","url":null,"abstract":"Precipitation interpolation is widely used to generate continuous rainfall surfaces for hydrological simulations. However, increasing the precision of values at the unknown points generated by different spatial interpolation methods is challenging. This study used the Chaohe River Basin, which is an important source of Beijing’s drinking water, as a research area to comprehensively evaluate several precipitation interpolation methods (Thiessen polygon, inverse distance weighting, ordinary kriging and ANUSPLIN) for inputs in hydrological simulations. This research showed that the precipitation time-series surface generated using the ANUSPLIN interpolation method had higher accuracy and reliability. Using this precipitation input to drive the hydrological models, we explored the parameter uncertainties of four typical hydrological models (GR4J, IHACRES, Sacramento and MIKE SHE) based on the multi-objective generalized likelihood uncertainty estimation (GLUE) method. The GLUE method was used to study the parameter sensitivity and uncertainty of the model. Results showed that the ANUSPLIN precipitation interpolation surface combined with the Sacramento model performed best. The multi-objective GLUE method had obvious advantages in parameter uncertainty analysis in hydrological models. Simultaneously exploring the convex line and point density distributions of the behavioural parameters with multi-objective functions determined their distribution and sensitivity more effectively.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"93 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80683059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-27DOI: 10.17159/wsa/2022.v48.i3.3892
Vurayai Ruhanya, N. Zhou, C. Berejena, G. Nyandoro, Paradzai Chibukira, A. Mukaratirwa, Simon Takawira Muserere, Kudzai Masunda, J. Meschke
Environmental surveillance is a sensitive method for detecting circulating virus in the absence of clinical cases and is important for monitoring progress for poliovirus (PV) eradication. This study used the bag-mediated filtration system (BMFS) to determine PV and enterovirus (EV) prevalence in sewage at the transition from oral polio vaccine type 2 (OPV2) use to inactivated polio vaccine (IPV) use in Zimbabwe, and examined the correlation between environmental surveillance results and vaccination coverage of OPV. A total of 18 BMFS samples from 6 sampling sites were analysed for the presence of EV and PV via direct RT-qPCR, direct ITD (intratypic differentiation), and the WHO algorithm. EV prevalence in Harare wastewater was 88.9% (16/18) using direct RT-PCR, 61.1% (11/18) using direct ITD, and 77.8% (14/18) using the WHO algorithm. Of the 18 samples analysed using the WHO algorithm, 10 samples (55.6%) were positive for Sabin-like PV type 3 (SL3). Of these 10 samples, 2 were also positive for non-polio enteroviruses (NPEV), resulting in a total of 6 (33.3%) samples positive for NPEV and 4 negative. The sensitivity of isolation in detecting EVs in sewage was 92.9% when comparing direct RT-qPCR results to the WHO algorithm. Using direct ITD, two high-density, low-income sampling sites were negative for SL3 and one low-density, high-income sampling point was negative for SL3 using the WHO algorithm. There was a strong association between relative EV concentration and the number of OPV3 vaccine recipients (r = 0.8590; p = 0.0284) in sampled areas. This study demonstrated the ability of BMFS to detect PVs circulating in Harare wastewater at the beginning of the OPV–IPV switch and can be used to monitor potential reintroduction of wild PV or vaccine-derived PVs from endemic areas.
{"title":"Recovery of enteroviruses and poliovirus in Harare sewage using the bag-mediated filtration system at the introduction of the inactivated polio vaccine in Zimbabwe","authors":"Vurayai Ruhanya, N. Zhou, C. Berejena, G. Nyandoro, Paradzai Chibukira, A. Mukaratirwa, Simon Takawira Muserere, Kudzai Masunda, J. Meschke","doi":"10.17159/wsa/2022.v48.i3.3892","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i3.3892","url":null,"abstract":"Environmental surveillance is a sensitive method for detecting circulating virus in the absence of clinical cases and is important for monitoring progress for poliovirus (PV) eradication. This study used the bag-mediated filtration system (BMFS) to determine PV and enterovirus (EV) prevalence in sewage at the transition from oral polio vaccine type 2 (OPV2) use to inactivated polio vaccine (IPV) use in Zimbabwe, and examined the correlation between environmental surveillance results and vaccination coverage of OPV. A total of 18 BMFS samples from 6 sampling sites were analysed for the presence of EV and PV via direct RT-qPCR, direct ITD (intratypic differentiation), and the WHO algorithm. EV prevalence in Harare wastewater was 88.9% (16/18) using direct RT-PCR, 61.1% (11/18) using direct ITD, and 77.8% (14/18) using the WHO algorithm. Of the 18 samples analysed using the WHO algorithm, 10 samples (55.6%) were positive for Sabin-like PV type 3 (SL3). Of these 10 samples, 2 were also positive for non-polio enteroviruses (NPEV), resulting in a total of 6 (33.3%) samples positive for NPEV and 4 negative. The sensitivity of isolation in detecting EVs in sewage was 92.9% when comparing direct RT-qPCR results to the WHO algorithm. Using direct ITD, two high-density, low-income sampling sites were negative for SL3 and one low-density, high-income sampling point was negative for SL3 using the WHO algorithm. There was a strong association between relative EV concentration and the number of OPV3 vaccine recipients (r = 0.8590; p = 0.0284) in sampled areas. This study demonstrated the ability of BMFS to detect PVs circulating in Harare wastewater at the beginning of the OPV–IPV switch and can be used to monitor potential reintroduction of wild PV or vaccine-derived PVs from endemic areas.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"27 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84478173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-27DOI: 10.17159/wsa/2022.v48.i3.3959
Balamlile Z Zondo, O. Sadare, G. S. Simate, K. Moothi
Purification of wastewater before it is discharged into the aquatic environment is important in order to prevent pollution of clean water. This study investigated the applicability of functionalized multi-walled carbon nanotubes (MWCNTs) decorated with gold-iron oxide nanoparticles for the adsorptive removal of Pb2+ from synthetic wastewater. CNTs were commercially obtained and functionalized with a mixture of H2SO4/HNO3 acids. The CNTs were coated with gold-iron oxide nanoparticles, to enhance the adsorption of heavy metals. The gold-iron oxide nanoparticles were synthesized by reacting green tea leaf extract with iron chloride (FeCl2) and gold (III) chloride (HAuCl4) precursors. The composite was cross-linked using N, N-dimethylformadide (DMF). The adsorbents were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to assess their surface morphology, Fourier transform infrared (FTIR) spectroscopy to identify the functional groups present, X-ray diffraction (XRD) to ascertain the crystallographic structure of the green adsorbent and Raman spectroscopy to determine the sample purity. SEM results showed highly agglomerated and polydispersed nanoparticles, owing to the presence of phytochemicals in the tea extract and magnetic interaction between the individual particles indicating the successful synthesis of Au/Fe3O4 adsorbent. Furthermore, an increase in the amount of Pb2+ removed per unit mass (qe) of adsorbent from 1.233 to 7.266 mg‧g-1 at 298 K was observed. A high sorption capacity was noticed for MWCNT-Au/Fe3O4 as compared to the MWCNT-COOH. The Pb2+ removal percentage increased from 50% to 78% with an increase in MWCNT-Au/Fe3O4 dosage from 0.02 g to 0.1 g. Adsorption isotherm data fitted well to the Freundlich and Langmuir isotherm models for MWCNT-COOH and MWCNT-Au/Fe3O4 adsorbents and the rate of Pb(II) adsorption by MWCNT-Au/Fe3O4 encountered an increase with increasing solution temperature and followed the pseudo-second-order model. The synthesized MWCNT-Au/Fe3O4 has good potential in removing heavy metals from wastewater.
{"title":"Removal of Pb2+ ions from synthetic wastewater using functionalized multi-walled carbon nanotubes decorated with green synthesized iron oxide–gold nanocomposite","authors":"Balamlile Z Zondo, O. Sadare, G. S. Simate, K. Moothi","doi":"10.17159/wsa/2022.v48.i3.3959","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i3.3959","url":null,"abstract":"Purification of wastewater before it is discharged into the aquatic environment is important in order to prevent pollution of clean water. This study investigated the applicability of functionalized multi-walled carbon nanotubes (MWCNTs) decorated with gold-iron oxide nanoparticles for the adsorptive removal of Pb2+ from synthetic wastewater. CNTs were commercially obtained and functionalized with a mixture of H2SO4/HNO3 acids. The CNTs were coated with gold-iron oxide nanoparticles, to enhance the adsorption of heavy metals. The gold-iron oxide nanoparticles were synthesized by reacting green tea leaf extract with iron chloride (FeCl2) and gold (III) chloride (HAuCl4) precursors. The composite was cross-linked using N, N-dimethylformadide (DMF). The adsorbents were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to assess their surface morphology, Fourier transform infrared (FTIR) spectroscopy to identify the functional groups present, X-ray diffraction (XRD) to ascertain the crystallographic structure of the green adsorbent and Raman spectroscopy to determine the sample purity. SEM results showed highly agglomerated and polydispersed nanoparticles, owing to the presence of phytochemicals in the tea extract and magnetic interaction between the individual particles indicating the successful synthesis of Au/Fe3O4 adsorbent. Furthermore, an increase in the amount of Pb2+ removed per unit mass (qe) of adsorbent from 1.233 to 7.266 mg‧g-1 at 298 K was observed. A high sorption capacity was noticed for MWCNT-Au/Fe3O4 as compared to the MWCNT-COOH. The Pb2+ removal percentage increased from 50% to 78% with an increase in MWCNT-Au/Fe3O4 dosage from 0.02 g to 0.1 g. Adsorption isotherm data fitted well to the Freundlich and Langmuir isotherm models for MWCNT-COOH and MWCNT-Au/Fe3O4 adsorbents and the rate of Pb(II) adsorption by MWCNT-Au/Fe3O4 encountered an increase with increasing solution temperature and followed the pseudo-second-order model. The synthesized MWCNT-Au/Fe3O4 has good potential in removing heavy metals from wastewater.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"29 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85533823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-27DOI: 10.17159/wsa/2022.v48.i3.3893
Sofia MG Rocha, Maria de JD Rocha, Germário M Araújo, Helena Becker, Iran E Lima Neto
This study evaluates the residence time (RT) and total phosphorus (TP) in a small hypereutrophic lake in the city of Fortaleza, Brazil. The results indicate that RT predicted by a complete-mix model is very similar (R² = 0.83) to that simulated with a 2-D hydrodynamic model (CE-QUAL-W2). Simple power-laws were fitted to describe RT and TP concentration at the lake inlet as functions of lake inflow, yielding correlations of R² = 0.84 and 0.70, respectively. The combination of these correlations with a complete-mix approach provided a comprehensive model that predicted TP values measured at the lake outlet reasonably well (R² = 0.60). In addition, a direct empirical correlation between simulated TP concentration and precipitation was also obtained. The simulations indicate a nearly periodic behaviour of RT and TP, with the seasonal variations being much higher than the interannual ones. Finally, an application of the model showed that a reduction of 99% of the input TP load was required to reach 100% compliance with the required water quality standards; this could be achieved by connecting the residences to the sewage network. The methodology proposed in this research can be easily applied to other lakes in the Brazilian northeast and extended to other tropical regions around the globe.
{"title":"Seasonal and interannual variability of residence time and total phosphorus in a small hypereutrophic lake in the Brazilian northeast","authors":"Sofia MG Rocha, Maria de JD Rocha, Germário M Araújo, Helena Becker, Iran E Lima Neto","doi":"10.17159/wsa/2022.v48.i3.3893","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i3.3893","url":null,"abstract":"This study evaluates the residence time (RT) and total phosphorus (TP) in a small hypereutrophic lake in the city of Fortaleza, Brazil. The results indicate that RT predicted by a complete-mix model is very similar (R² = 0.83) to that simulated with a 2-D hydrodynamic model (CE-QUAL-W2). Simple power-laws were fitted to describe RT and TP concentration at the lake inlet as functions of lake inflow, yielding correlations of R² = 0.84 and 0.70, respectively. The combination of these correlations with a complete-mix approach provided a comprehensive model that predicted TP values measured at the lake outlet reasonably well (R² = 0.60). In addition, a direct empirical correlation between simulated TP concentration and precipitation was also obtained. The simulations indicate a nearly periodic behaviour of RT and TP, with the seasonal variations being much higher than the interannual ones. Finally, an application of the model showed that a reduction of 99% of the input TP load was required to reach 100% compliance with the required water quality standards; this could be achieved by connecting the residences to the sewage network. The methodology proposed in this research can be easily applied to other lakes in the Brazilian northeast and extended to other tropical regions around the globe.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79046313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-27DOI: 10.17159/wsa/2022.v48.i2.3900
JM Winter, C Loubser, A Bosman
The standard design and cost estimation for a sewer network involves considerable time and financial investment. There are, however, many cases where a rapid assessment of the sewer infrastructure or related costs associated with a service zone might be required. Although there are numerous approaches to rapid sewer infrastructure estimation in the literature, to date, no widely available tool has been developed that can be applied to reliably estimate the expected sewer pipeline infrastructure associated with a service zone in South Africa. The aim of this study was to develop a method for estimating the sewer pipeline infrastructure required for a service zone, based on limited information, that could be applied to future developments. A database of South African sewer network data was used in the development of three major study outcomes. Study Outcome I involved developing regression models for estimating the total sewer pipeline length using only basic service zone characteristics. Models were developed for different categories of land use and area size, allowing for estimation of the total pipeline length as a function of the service zone area size, relief, and the density of contributing users. Study Outcome II involved determining the average pipeline diameter distributions for different types of service zones, enabling disaggregation of the total pipeline length into lengths per diameter. Study Outcome III involved determining the average number of manholes per kilometre of sewer pipeline. Combined, the three study outcomes form an infrastructure estimation tool that enables the sewer pipeline length per approximate diameter and the number of manholes associated with a service zone to be estimated, applicable to service zones smaller than 450 hectares. This study illustrates how the same methodology can be followed to develop similar tools which are applicable to other specific regions or development types, provided an appropriate dataset is obtainable.
{"title":"Estimating sanitary sewer pipeline infrastructure from basic characteristics of a service zone","authors":"JM Winter, C Loubser, A Bosman","doi":"10.17159/wsa/2022.v48.i2.3900","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i2.3900","url":null,"abstract":"The standard design and cost estimation for a sewer network involves considerable time and financial investment. There are, however, many cases where a rapid assessment of the sewer infrastructure or related costs associated with a service zone might be required. Although there are numerous approaches to rapid sewer infrastructure estimation in the literature, to date, no widely available tool has been developed that can be applied to reliably estimate the expected sewer pipeline infrastructure associated with a service zone in South Africa. The aim of this study was to develop a method for estimating the sewer pipeline infrastructure required for a service zone, based on limited information, that could be applied to future developments. A database of South African sewer network data was used in the development of three major study outcomes. Study Outcome I involved developing regression models for estimating the total sewer pipeline length using only basic service zone characteristics. Models were developed for different categories of land use and area size, allowing for estimation of the total pipeline length as a function of the service zone area size, relief, and the density of contributing users. Study Outcome II involved determining the average pipeline diameter distributions for different types of service zones, enabling disaggregation of the total pipeline length into lengths per diameter. Study Outcome III involved determining the average number of manholes per kilometre of sewer pipeline. Combined, the three study outcomes form an infrastructure estimation tool that enables the sewer pipeline length per approximate diameter and the number of manholes associated with a service zone to be estimated, applicable to service zones smaller than 450 hectares. This study illustrates how the same methodology can be followed to develop similar tools which are applicable to other specific regions or development types, provided an appropriate dataset is obtainable.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"6 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90534109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-27DOI: 10.17159/wsa/2022.v48.i2.3890
Sisipho Ngebe, Kasongo Benjamin Malunda, Anja du Plessis
To achieve informed integrated water resource management and sustainability, an understanding of the quantity of water available for use within a spatial and temporal context is needed. This study was consequently focused on the estimation of water levels with the use of geospatial techniques. The availability of water data is a significant challenge, especially for smaller dams used by farmers. The lack of consistent water data in turn poses a problem by limiting the estimation of the overall water availability in water strategy models. This challenge is attributed to the cost of modeling all available water resources and the lack of complete records of all available water resources, as some small dams are not officially registered. This paper provides a simple protocol that can be implemented to reliably derive water levels for dams that are yet to be registered or accounted for, using the Katrivier Dam as a case study. Three main datasets were used which enabled the calculation of water levels – a 12.5 m digital elevation model, Sentinel-2 optical images, and water data from the Department of Water and Sanitation (DWS), as in-situ data. The resulting water level values were derived using a proposed model that includes two correction factors, k and s. The results obtained showed that the estimated water levels from the model proposed in this paper are analogous with those observed by the DWS. Therefore, the proposed method can serve as an additional cost-effective method in water accounting procedures as it requires less expensive equipment than alternatives such as bathymetric methods.
{"title":"Utility of geospatial techniques in estimating dam water levels: insights from the Katrivier Dam","authors":"Sisipho Ngebe, Kasongo Benjamin Malunda, Anja du Plessis","doi":"10.17159/wsa/2022.v48.i2.3890","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i2.3890","url":null,"abstract":"To achieve informed integrated water resource management and sustainability, an understanding of the quantity of water available for use within a spatial and temporal context is needed. This study was consequently focused on the estimation of water levels with the use of geospatial techniques. The availability of water data is a significant challenge, especially for smaller dams used by farmers. The lack of consistent water data in turn poses a problem by limiting the estimation of the overall water availability in water strategy models. This challenge is attributed to the cost of modeling all available water resources and the lack of complete records of all available water resources, as some small dams are not officially registered. This paper provides a simple protocol that can be implemented to reliably derive water levels for dams that are yet to be registered or accounted for, using the Katrivier Dam as a case study. Three main datasets were used which enabled the calculation of water levels – a 12.5 m digital elevation model, Sentinel-2 optical images, and water data from the Department of Water and Sanitation (DWS), as in-situ data. The resulting water level values were derived using a proposed model that includes two correction factors, k and s. The results obtained showed that the estimated water levels from the model proposed in this paper are analogous with those observed by the DWS. Therefore, the proposed method can serve as an additional cost-effective method in water accounting procedures as it requires less expensive equipment than alternatives such as bathymetric methods.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"19 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77728146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-27DOI: 10.17159/wsa/2022.v48.i2.3908
Zakaria A Mohamed, Saad Alamri, Mohamed Hashem
The present study determines the endotoxin removal efficiency of drinking water treatment plants (DWTPs) in Egypt, as examples of conventional treatment methods used in developing countries. The total endotoxin in source water (Nile River) of these DWTPs ranged from 57 to 187 EU∙mL−1, depending on the location of treatment plants. Coagulation/ flocculation/sedimentation (C/F/S) after chlorine pre-oxidation removed bound endotoxins by 76.1–85.5%, but caused cell lysis and increased free endotoxins by 28.2–33.3% of those detected in raw waters. Rapid sand filtration had not significant effect on free endotoxins, but reduced bound endotoxins by 23–33.3%. Final chlorine disinfection also reduced bound endotoxins to levels around 1 EU/mL, accompanied by an increase in free endotoxins (37–112 EU∙mL−1) in finished waters. Simultaneously, final chlorine disinfection removed all heterotrophic bacteria, with low cyanobacterial cell numbers (348–2 450 cells∙mL−1) detected in finished waters. Overall, conventional treatment processes at these DWTPs could removal substantial amounts of bound endotoxins and bacterial cells, but increase free endotoxins through cell lysis induced by pre-oxidation and final chlorine disinfection. The study suggests that conventional processes at DWTPs should be optimized and upgraded to improve their performance in endotoxin removal and ensure safe distribution of treated water to consumers.
{"title":"Endotoxin removal efficiency in conventional drinking water treatment plants, a case study in Egypt","authors":"Zakaria A Mohamed, Saad Alamri, Mohamed Hashem","doi":"10.17159/wsa/2022.v48.i2.3908","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i2.3908","url":null,"abstract":"The present study determines the endotoxin removal efficiency of drinking water treatment plants (DWTPs) in Egypt, as examples of conventional treatment methods used in developing countries. The total endotoxin in source water (Nile River) of these DWTPs ranged from 57 to 187 EU∙mL−1, depending on the location of treatment plants. Coagulation/ flocculation/sedimentation (C/F/S) after chlorine pre-oxidation removed bound endotoxins by 76.1–85.5%, but caused cell lysis and increased free endotoxins by 28.2–33.3% of those detected in raw waters. Rapid sand filtration had not significant effect on free endotoxins, but reduced bound endotoxins by 23–33.3%. Final chlorine disinfection also reduced bound endotoxins to levels around 1 EU/mL, accompanied by an increase in free endotoxins (37–112 EU∙mL−1) in finished waters. Simultaneously, final chlorine disinfection removed all heterotrophic bacteria, with low cyanobacterial cell numbers (348–2 450 cells∙mL−1) detected in finished waters. Overall, conventional treatment processes at these DWTPs could removal substantial amounts of bound endotoxins and bacterial cells, but increase free endotoxins through cell lysis induced by pre-oxidation and final chlorine disinfection. The study suggests that conventional processes at DWTPs should be optimized and upgraded to improve their performance in endotoxin removal and ensure safe distribution of treated water to consumers.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":"11 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84264443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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